Safety device for motion picture projectors



Nov. 20, 1934. M. SCHEINFELD SAFETY DEVICE FOR MOTION PICTURE PROJEGTORS Filed July 14, 1931 3 Sheets-Sheet l Inventor: -Mnis'SclwgZd .flllorn 05/ Nov. 20, 1934. M. SCHEINFELD SAFETY DEVICE FOR IOTION PICTURE PHOJECTORS Filed July 14, 1931 3 Sheets-Sheet 2 l IIII/II/I/ NOV. 20, 1934. SCHEINFELD 1,981,670

SAFETY DEVICE FOR MOTION PICTURE PROJECTORS Filed July 14, 1931 3 Sheets-Sheet 3 Wf/A Indemn- Patented Nov. 20, 1934 UNITED STATES SAFETY DEVICE FOR MOTION PICTURE PROJECTO Morris Scheinteld,

Philadelphia, Pa.

Application July 14, 1931, Serial No. 550,638

11 Claims.

My invention relates to safety devices for motion picture projectors, and it relates more particularly to improved means for automatically stopping the driving motor in the event of any abnormal condition arising, for preventing fires in the event that the film is not fed properly through the machine, and for extinguishing such fires as may occur, so that the same will be prevented from reaching the main body of the film within the magazines.

It is, of course, well known that in the operation of motion picture projectors, in the event of the film stopping or being slowed up, the same is likely to be ignited by reason of the intense heat of the light beam being concentrated too long on one portion of the film. It will be understood that should the film become ignited between the magazines, and the motor continues to operate (the film thereby being fed from the magazine), a considerable portion of the same is likely to be destroyed, particularly if the operator should abandon the machine without shutting off the power, and in many instances the fire will extend to the main body of the film within the magazines.

The principal object of my invention, therefore, is to provide improved means, adaptable for use in connection with motion picture projectors of the types at present in common use, for intercepting the beam of light and bringing the motor'to a stop, in the event of unusual conditions, such as stoppage or slowing up of the feed of the film, or the breaking of the film between the magazines.

A further object of my invention is to provide improved apparatus of the character aforesaid adapted to have incorporated therein means for automatically extinguishing any fire which may occur between the magazines, whereby the same will be prevented from reaching the main body of the film, and will be confined to the exposed portions thereof. v

A further object of my invention is to provide improved means, adaptable for the purposes aforesaid, which will be simple, efficient and certain in its action, and which may be readily used on existing types oi motion picture projectors.

' The nature and characteristic features of m invention will be more readily understood from the following description, taken in connection with theaccompanying drawings forming part hereof, in which:

Figure 1 is a diagrammatic view, illustrating an arrangement of circuits and devices embodying the main'features of my present invention;

Fig. 2 is a front elevation, partly broken away, of an automatic dowser and switch device adapted to intercept the beam of light and to control certain of the circuits in the event of the film not being properly fed between the magazines; I

Fig. 3 is a horizontal section, taken approximately on the line 3-a of Fig. 2;

' Fig. 4 is a transverse section, taken approximately on the line 4-4 of Fig. 2;

- Fig. 5 is a vertical sectional view of a portion of a motion picture projector adjacent one of the film magazines, illustrating in detail a device'for extinguishing fire between the magazines, whereby the fire will be prevented from reaching the main body of the film, said device being adapted to be used in connection with my invention;

Fig. 6 is a horizontal section thereof, taken approximately on the line 66 of Fig. 5; and

Fig. 7 is a vertical section thereof, taken approximately on the line 7-7 of Fig. 5.

It will, of course, be understood that the description and drawings herein contained are illustrative merely, and that various changes and modifications may be made in the structure disclosed without departing from the spirit of my invention.

Referring now more particularly to Fig. 1 of the drawings, as there shown wand 11 are the main power leads, supplied with electrical current from any suitable source of supply. A wire 12. extends from lead 10 to one of the terminals of the motor 13 which operates the motion picture projection machine.

The other terminal of the motor 13 is connected by wire 14 to contact 15 of a relay 16. The other contact 17 of relay 16 is connected by wire 18 to power lead 11. The contacts 15 and 1'? of the relay 16 are adapted, when the coil thereof is energized, to be bridged by a contact bar 19.

A wire 20 extends from lead 10 to a switch 21. The switch 21 is normally held on contact 22 by means of a spring 23.. Contact 22 of switch 21 is connected by wire 24 to the coil 25 of relay 16, which controls the-circuit in which the motor for operating the motion picture projection machine is included.

The other end of the coil 25 of relay 16 is connected by wire 26 to one of the contacts 27 of a switch which is provided in connection with 1 contact bar 32, as will also be hereinafter more fully set forth.

A shunt line extends from line 24 to one end of an electro-magnetic coil 36, provided for the control of a dowser, as will be hereinafter more fully set forth. The other end of the coil 36 is connected by wire 3'7 to one pole of a normally closed switch 38, which is adapted to be automatically opened when the dowser is I released, as will also be hereinafter set forth in connection with the description of the dowser mechanism.

The other pole of the switch 38 is connected by wire 39 to one end of an electro-magnetic coil 40, forming part of one of the fire extinguishing devices 28, which will be hereinafter more fully described. The other end of the coil 40 is connected by wire 41 to one end of the coil of the other fire extinguishing device 28. The other end of the coil of the other fire extinguishing device 28 is connected by wire 42 to wire 31 which, as hereinbefore stated, extends to the power lead 11.

A pair of switches 45 is interposed in the line 39, these switches being of a type well'known and in common use in safety devices for motion picture projection machines. Each switch has an arm 46 provided with a part at the end thereof which bears against the exposed portion of the passing film 47. The arrangement is such that, in the event of breakage of the film, either mechanically or by reason of its becoming ignited,

one or both of saidswitches will be automatically opened to break the circuit of which the line 39 forms a part. c

A line 50 is shunted from line 35 which extends to one end of the dowser control coil 36. Line 50 extends to a contact 51, provided in connection with a speed responsive device 52. Another contact 53 of said speed responsive sive device 52 is provided with a member 55,-

which is adapted to bridge the contacts 51 and 53 when the'low limit of speed is reached, and thereby the coil 36 of the dowser mechanism is shunted and de-energized by reason of the resistance of the shunt circuit being less than that of the coil.

. The dowser mechanism and its associated parts are shown in detail in Figs. 2, 3 and 4 of the drawings. The internal parts thereof are enclosed within a. housing 60, which is adapted to be mounted on the condenser lens hood 61 of the projection machine. On the front end of the housing 60 is mounted a cover-plate 62. A horizontal shaft 63. is journaled at the rear end of the housing 60, and near its frontend in the cover plate 62.

An arm 64 is secured upon the front end of the shaft 63. The arm 64 carries at its lower end a dowser plate 65, which is adapted to be swung in front of the lens hood 61 when it is desired to intercept the beam of light from the lamp housing. The upper end of the arm 64 carriesa knob 69 for the manual actuation of the dowser. The upper end of the arm 64 also carries a lug 66, which is adaptedywhen the dowser is in the dropped or intercepted position, to be engaged by a retaining latch 6'7, thereby to insure the retention of the dowser plate in the intercepting position after the same has been released. A coil spring 68 tends to impel the dowser at all times toward the intercepting position.

Secured to the shaft 63 is a lever '70, provided with a finger 71 at its outer end. The finger '71 of lever '70 is adapted to be engaged by a hooklike lamh '72. The latch '72 is connected to an arm '73 which carries an armature '74 at its forward end. The latch and armature parts are pivotally mounted by means of a pin 75, mounted in lugs '76 projecting inwardly from one of the side walls of the housing 60.

The armature 74 is adapted to be attracted and retained by the pole pieces of the coil or electro-magnet 36, mounted within the housing 60. The arrangement of the foregoing parts is such that when the armature '74 is attracted and retained by the electro-magnet 36, it is adapted to hold the dowser plate 65 in the raised or non-intercepting position, as shown'in Figs. 2 and 3 of the drawings, permitting the same to fall. whenever 'the 'electro-magnet 36 is de-' energized.

A spring '79 tends to raise the latch '72 when the electro-magnet 36 is de-energized, thereby permitting the finger '71 to be brought into engagement beneath the latch '72 when the dowser 65 is swung to the light intercepting position.

The horizontal shaft 63 of the dowser mechanism is also provided with a lever arm 80, which is adapted, when the dowser plate is in the dropped or intercepting position, to engage a pin 81 and depress the same. The lower end of the pin 81 carries the switch bar 38, which is adapted to bridge the electrical contact members 82 and 83, to which lines 37 and '39 are respectively connected. Springs 84 normally impel the switch bar 35 to the contacting position whenthe dowseris in the raised or non-intercepting position, as shown in Figs. 2 and 3 of the drawings.

In Figs. 5, 6 and '7 of the drawings, there is shown a preferred form of fire extinguishing device, adapted to be used in connection with the reel magazines of a motion picture projector. As there shown, 90 is a portion of the reel magazine to which the housing 91 of the fire extinguishing device is attached in any suitable manner.

Guide wheels 92 are journaled in the housing 91, by means of shafts 93. The guide wheels 92 are arranged in pairs, at the top and bottom of the housing 91, and serve to guide the film 4'7 in front of a. plate 95, so that the surface of the film will norm ally be held away from the surface of the plate 95..

The guide rollers 92 have their central portions reduced in diameter, so that only the larger ends of said rollers will grip the film 4'7, onthat portion of the same which contains-no pictures,

thus avoiding any possibilty of the rollers marring the picture surface of the film.

Arranged adjacent the plate 95 is another plate 96, which is preferably made of magnetic material, such as soft iron. The plate 96 is carried at the front end of a series of rods 9'7, which are slidably mounted in the flanges 98 of the electro-magnetic coil 40. Springs 100 are mounted on therods 97, and tend to impel the rods forwardly, and consequently to impel plate 96 toward plate 95.

It will, of course, be understood that when the coil 40 is energized by the passage of an electrical current therethrough, the plate 96 will be held retracted against the tension of the springs 100, and in this position the plate 96 will be free from contact with the passing film 47.

One of the side walls of the housing 91 is slotted, as at 101, to permit the film to be more conveniently threaded through the safety device, and this slot is so located as to be closed by the plate 96 when the same is released by the de-energization of the coil 40, so that when the plate 96 is in the position to grip the film 47, the filmwill be entirely enclosed, not only on the surfaces of the portion thereof which is between the plates 95 and 96, but also at the edges.

The rear ends of the rods 97 carry a yoke 102, preferably made of an insulating material such as vulcanized fiber. The contact bar 32 is carried by the yoke 102, preferably by means of pinsv 104, which permit a limited range of movement of the contact bar 32 with respect to the yoke 102. Springs 105 are interposed between the contact bar 32 and the yoke 102.

The contact bar 32 is adapted, when the plate 96 is retracted by the energization of the coil 40, to establish an electrical contact between the contact members 27 and 29. The contact members 27 and 29 are mounted in the housing 91, being insulated therefrom by-suitable insulating washers 108. The outer ends of the contact members are threaded for the attachment of the electrical lines hereinbefore described.

The operation of the device may now be explained In Figs. 1 to 3, and 5 and 6, the parts are in the positions assumed when the motion picture projector is properly operating, and so long as the coil 25 of relay 16 is maintained energized, the current will flow from power lead 10, through wire 12, to motor 13, thence by wire 14, contact 15, relay contact bar 19, contact 17, and wire 18, to the other power lead 11.

When, however, .the coil 25 of relay 16 becomes de-energized by failure of the current to pass therethrough, the contact bar 19 will drop, and the motor circuit thus be opened, whereupon the motor will of course cease to operate.

In the normal operation of the machine, the current passes from the main power lead 10, through wire-20 to switch 21, and as the arm thereof is normally held on contact 22 by spring 23, the current will pass by line 24 to coil 25 of relay 16, thence by wire 26 to contact 2'1, through contact bar 32, contact bar 29 of one of the fire extinguishing devices 28, to line 30, thence to contact 2'7, through contact bar 32,

v to contact 29, and thence by wire 31 to the other power lead 11.

.It will be noted, however, that whenever the coil 40 of either of the fire extinguishing devices 28 is de-energized by the failure of current to pass therethrough, the corresponding contact bar 32 will be carried away from contacts 2'? and 29, thus opening the circuit in which-the coil 25 of relay 16 is included. It therefore follows that whenever the switch provided by the contact bar 32 and the contacts 27 and 29 of either of the fire extinguishing devices is opened, the relay 16 will cause the motor circuit to be opened as hereinbefore described, and the motor thereby stopped.

Whenever the motion picture projection machine is functioning properly, the dowser will be in the non-intercepting position, the switch 38 associated therewith will be in the closed position, and the film controlled switches 45 will be in their closed positions. When these parts are in such positions, the current will flow from the shunt line 35 which extends from line 24, to the dowser controlling coil 36, thence by wire 37 to switch 38, thence by line 39, through switches 45 which are included in said line 39, to the coil 40 of one of the fire extinguishing devices 28, thence by wire 41 to the coil 40 of the, other fire extinguishing device 28, and thence by line 42 to line 31, which as hereinbefore de scribed is connected to power lead 11.

It will thus be seen that, so long as the dowser controlled switch 38 and the film controlled switches 45 are in their normal positions, th coils 40-=of the fire extinguishing devices 28 will be maintained in an energized condition, thus retracting the plates 96 from contact with the film 47, and maintaining the contact bars 32 in engagement with the contact members 27 and 29, for the purpose hereinbefore set forth. Likewise, when the current is passing as aforesaid, the dowser controlling coil 36 will be energized and the dower held in the non-intercepting position. a

In the event of the film becoming broken or ignited, one or both of the switches 45 will be opened, whereupon the dowser controlling coil 36 will become de-energized, permitting the dowser to fall to the light intercepting position. At the same time, the coils 40 of the fire extinguishing devices will become de-energized, and the plate 96 will be permitted to clamp the film against the plates 95, thereby preventing the fire from passing into the reel magazines. At the same time, the circuit in which the relay coil 25 is included, as hereinbefore set forth, will be opened, thus de-energizing the coil 25 of relay 16, whereupon the motor circuit will be opened as hereinbefore described.

In-the event that the speed of the film should become reduced to a dangerous minimum, the speed responsive device 52 will cause a contact to be established by means of the member 55 coming in contact with the contact members 51 and 53. As the shunt line controlled by this device is of less resistance than the dowser controlling coil 36, said coil m'll become deenergized, whereupon its armature will be released, and the latch 72 raised sufilciently to release the dowser and permit the same to fall to the light intercepting position. When this occurs, the lever will cause the switch 38 to be opened, thus breaking the circuit in which the coils 40 of the fire extinguishing devices are included, and permitting the same to function in the same manner as when the switches 45 are opened.-

It is desirable, for the purpose of threading the film through the projector, to retract'the plates of the fire extinguishing device for a short period of time while the dowser is in the light intercepting position,-and for this purpose the shuntline 110 is provided, which extends from a contact 111 of switch 21 to line 39, at such a point in line 39 as to permit the-current to be fed to the coils 40 of the fire extinguishing devices 28 when the arm of the switch 21 is on the contact member 111.

When the arm of the switch 21is on the contact member 111, the current will flow from power lead 10, through line 20 to switch 21, to contact 111, thence by line 110 to line 39, thence to the coil 40 of one of the fire extinguishing devices 28, then by line 41 to the coil 40 of the other fire extinguishing device 28, thence by line 42 to line 31, which as hereinbeiore set forth extends to the other power lead 11.

.When the arm of the switch 21 is on the contact member 111, the circuit in which the coil 25 of relay 16 is included is open, by reason of the arm of the switch being oil the contact 22, and hence the contact bar 19 of the relay will be away from its contact members 15 and 1'I, and the motor circuit thereby opened. The switch 21 is of such type that it will normally be held on the contact 22 by the spring 23, and

can only be made to engage the contact 111 by the arbitrary actuation of the operator.

The switch 21 may also be used by the operator for the purpose of quickly stopping the motor and dropp ng the dowser, whenever, for any reason, occasion arises to do so.

I claim:

1. In a motion picture projection machine, a'

. er for opening said switch when the dowser is m the light intercepting position, and means controlled by said shunt circuit for opening and closing the relay coil circuit.

2. In a motion picture projection machine, a motor circuit, a relay for controlling said motor circuit, a circuit independent of the motor circuit in which the coil or said relay is included, a dowser, an electro -magnet adapted when energized to hold said dowser in the operating position, saidrnagnet being, included in a normally closed shunt of the relay coil circuit, a switch in said shunt circuit, means associated with, the dowser for opening said switch when the dowser is in the light intercepting position, switches for controlling said shunt circuit having members engaging the film whereby said switches will" be opened in the event of breakage or disarrangement of the film, and means controlled by raid shunt circgliz for opening and closing the relay coil circ 3.. In a motion picture projection machine, a.

motor circuit, a. relay for controlling said. motor circuit, a circuit independent of the motor circuit in which the coil 'ofsaid relay-is included, a dowser, an electro-magnet' adapted when energized to hold said dowser in the operating position, said magnet being included in a normally closed shunt of the relay coil circuit, a switch in said shunt circuit, means associated with" the dowser for opening said switch when the dowser is in the light intercepting position, normally closed switches in series in said shunt circuit having members engaging the film whereby said switches will be opened in the event of breakage or disarrangee vices, a switch operated by said fire extinguishing devices for controlling the relay coil circuit, a normally closed circuit in which the coils of the fire extinguishing devices are included, switches for controlling said circuit having members -engaging the film whereby said switches will be opened in the event of breakage Y or disarrangement of the film and thus permit the fire extinguishing devices to be actuated.

5. In a motion picture projection machine, a

motor circuit, a relay for controlling said motor circuit, a circuit independent of the motor circuit in which the coil of said relay is in- -cluded, electro-magnetic fire extinguishing devices, a switch operated by said fire extinguishing devices for controlling the relay coil circuit, a normally closed circuit in which the coils of the fire extinguishing devices are included, switches for controlling said circuit having members engagin the film whereby said switches will be opened in the event'ot breakage or disarrangement oi the film; and means for separately energizing the coib of the fire extinguishing devices at will comprising a shunt line, and a switch adapted to open the line ex tending to the coil of I the relay and simultaneously pass the current by means of said shunt line to the coils of the fire extinguishing devices.

- 6. In a motion picture projection machine, a

motor circuit, a 'rolay or controlling said motor circuit, ,a circuit independent of the mo tor circuit "in which the coil of said relay is included, electro-magnetic fire extinguishing devices, a switch operated by said fire .extinguishing devices for controlling the relay coil circuit, a circuit in which the coils of the fire: extinguishing devices are included, a dowser, an 'electr'o-magnet for controllng said dowser, said magnet being included in the same circuit as the coils of the fire extinguishing devices, a

switchin said circuit, and means associated with the dowser for opening said switch when the dowser is in" the light intercepting position and thus permit the fire extinguishing devices to be actuated.

' '7. In a motion picture projection machine, a motor circuit, a relay for controlling said motor circuit, a circuit independent of ,the motor circuitin whichthe coil of said relay is included, electro-magnetic fire extinguishing devices, a switch operated by said fire extinguishing devices for controlling the relaycoil circuit, a

circuit in which the coils of the fire extin- 'guishing devices are included, a dowser, an electro-magnet for controlling said dowser, said magnet being includedin the same circuit as the manure in said circuit, means associated with the dowser for opening said switch when the dowser is in the light intercepting position, and switches for controlling said circuit having members engaging the film whereby said switches will be opened in the event of breakage or disarrangement of the film and thus permit the fire extinguishing devices to be actuated.

8. In a motion picture projection machine, a motor circuit, a relay for controlling said motor circuit, a circuit independent of the motor circuit in which the coil of said relay is included, electro-magnetic fire extinguishing devices, a switch operated by said fire extinguishing devices for controlling the relay coil circuit, a circuit in which the coils of the fire extinguishing devices are included, a dowser, an electro-magnet for controlling said dowser, said magnet being included in the same circuit as the coils oi the fire extinguishing devices, va switch in said circuit, means associated with the dowser for opening said switch when the dowser is in the light intercepting position, switches for controlling said circuit having members engaging the film whereby said switches will be opened in the event of breakage or disarrangement oi the film and means for de-energizing the dowser controlling magnet comprising a shunt circuit adapted to bypass the current around the dowser controlling magnet, and a speed responsive de-\ vice adapted to close said bypass circuit when the rate of feed of the film is decreased.

9. In a motion picture projection machine, a motor circuit, a relay for controlling said motor circuit, a circuit independent of the motor circuit in which the coil of said relay is included, electro-magnetic fire extinguishing devices, a switch operated by said fire extinguishing devices for controllingthe relay coil circuit, a circuit in which the coils of the fire extinguishing devices are included, a dowser, an electro-magnet for controlling said dowser, said magnet being included in the same circuit as the coils of the fire extinguishing devices, a switch in said circuit, means associated with the dowser for opening said switch when the dowser is in the light intercepting position, switches for controlling said circuit having members engaging the film whereby said switches will be opened in the event of breakage or disarrangement of the film; and means for separately energizing the coils of the fire extinguishing devices at will comprising a shunt line, and a switch adapted to open the line extending to the coil of the relay and simultaneously pass the current by means oi! said shunt line to the coils of the fire extinguishing devices.

10. In a motion picture projection machine, a motor circuit, a relay for controlling said motor circuit, a circuit independent of the motor circuit in which the coil of said relay is included, electro-magnetic fire extinguishing devices, a

switch operated by said fire extinguishing devices for controlling the relay coil circuit, a circuit in which the coils of the fire extinguishing devices are included, a dowser, an electro-magnet for controlling said dowser, said magnet being included in the same circuit as the coils of the fire extinguishing devices, a switch in said circuit, means associated with the dowser for opening said switch when the dowser is in the light intercepting position, switches for controlling said circuit having members engaging the film whereby said switches will be opened in the event of breakage or'disarrangement oi the film; means for de-energizing the dowser controlling magnet comprising a shunt circuit adapted to bypass the current around the dowser controlling magnet, and a speed responsive device adapted to close said bypass circuit when the rate of feed of the film is decreased; and means for separately energizing the coils of the fire extinguishing devices at will comprising a shunt line, and a switch adapted to open the line extending to the coil of the relay and simultaneously pass the current by means of said shunt line to the coils of the fire extinguishing devices.

11. In a motion picture projection machine, a motor circuit, a relay for controlling said motor circuit, a circuit independent of the motor circuit in which the coil of said relay is included, electro-magnetic fire extinguishing devices, a switch operated by said fire extinguishing devices ior controlling the relay coil circuit, a circuit in which the coils of the fire extinguishing devices are included, said circuit being shunted oil? the relay coil circuit, a dowser, an electromagnet for controlling said dowser, said magnet being included in the same circuit as the coils of the fire extinguishing devices, a switch in said circuit, means associated with the dowser for opening said switch when the dowser is in the light intercepting position, switches for controlling said circuit having members engaging the filrn whereby said switches will be opened in the event of breakage or disarrangement oi the film; means for de-energizing the dowser controlling magnet comprising a shunt circuit adapted to bypass the current around the dowser controlling magnet, and a speed responsive device adapted to close said bypass circuit when the rate of feed of the film is decreased; and means for separately energizing the coilsof the fire extinguishing devices at will comprising a shunt line, and a switch adapted to open the line extending to the coil of the relay and simultaneously pass the current by means of said shunt line to the coils of the fire extinguishing devices.

MORRIS SCHEINFELD. 

